1. Field of the Invention
The present invention relates to a method of controlling operation of a vehicle and, more particularly, to a method of controlling operation of a vehicle in which at least two different operations modes, whose operating parameters and/or control variables are calculated and/or determined within at least one time-slot pattern, are given in advance.
2. Prior Art
A method for processing of control parameters in an internal combustion engine control system is disclosed in German Patent Document DE 36 43 337 C2. In this method a first pulsed signal is produced for synchronization of the speed of the engine and a second pulsed time constant signal is produced for other purposes. These pulsed signals are present as interrupt signals at the interrupt input of a microprocessor. The microprocessor performs processing steps by which a number of control variables for the engine are controlled according to these interrupt signals. The control variables are based on data that represent the operating states of the internal combustion engine.
The individual processing steps first include processing steps for data to control a first group of control variables according to a rotation speed synchronized interruption called for by the first pulsed signal. A further processing of data in order to control a second group of control variables, according to a time-constant interruption, called for by the second pulsed signal occurs after that. A first flag is set during this processing in order to demand additional data during the rotation speed synchronized process and a second flag is set in order to demand or request additional data during the time-constant processing. Because of the setting of flags a plurality of further and additional data are processed during the absence of an interruption in order to improve the processing efficiency of the data. Since the rotation speed synchronization work has a higher priority, the processing of the second group of control variables is again undertaken when the processing of the first group is finished. Also other processing steps are performed as background processing in addition to both processing sequences, when the above-described interruptions do not occur. Because of this latter feature sufficient processing time and processing capacity are available at high engine speeds.
A method of calculating control variables for repeat control events is also described in German Patent Document DE 42 19 669 A1. In order to reduce bus load and avoid overflow of transferred data, the operating parameter transfer conditions are formulated according to whether or not the value of a calculated control variable has not changed from a given calculated value more than a predetermined limiting amount. When the change of the control variable is not greater than the predetermined limiting amount, the data transfer is suppressed. On the other hand, in order to reduce the required amount of calculations performed by the control device or control unit, the operating condition, whether or not values of particular control variables are already known to have the same values, is tested prior to calculation, so that control variables that are not to be transferred are not calculated at all.
The above-mentioned control method for an internal combustion engine is one application for the prior art method described above. A difference between rotation speed-synchronized and time-synchronized processes with their associated control variables is disclosed in German Patent Document DE 36 43 337 C2. In the method disclosed in this reference the rotation speed synchronized processes have the highest priority. Background processing is only possible when neither of the above-described two processes is active and when no interrupt signal is being processed. Because of these latter features of the method described in DE 36 43 337 C2, control variables are not instantaneously available but must be first calculated according to their respective priorities as required. Differences between two different operating modes of the engine are not accounted for in the method described in DE 35 43 337 C2.
Besides certain control variables are not calculated at all in the method described in DE 42 19 669 A1. A reduction of the processing load depends on the amount of the control variable changes. If the allowed variation in the control variables is too small, the goal of reducing the computational effort is not reached. In order to achieve a significant load reduction, a comparatively large variation in the control variables must be permitted. Because of that the control variables are not instantaneously available or there is a comparatively large tolerance for control variable changes. Here also differences due to two or more operating modes are not accounted for.
According to the prior art the required computations are performed entirely by themselves when possible or with selective functions shut off or suppressed with too great a computational load. Use of different time-slot patterns is not disclosed in the state of the art. Thus only one time-slot pattern is usually used because of the omission of different processing steps for two or more operating modes.
Differences due to different operating modes are accounted for however in internal combustion engine control, for example in connection with fuel injection processes. For example different load levels are taken into account during control of the engine at a partial load level and in operation at full load with a homogeneous mixture. This method is described, for example, in Motortechnischen Zeitschrift [Engine Engineering Journal] (MTZ 58, 1997, pp. 458 to 464) and Fachbuch Direkteinspritzung [Handbook for Direct Fuel Injection in Automobile Engines] (Expert Verlag [Press], ISBN 3-8169-1685-6, pp. 186 to 206). An optimization of the processing load on the engine control unit or in the engine control method is required because of the differences in the various operation modes and the transient changes between them.